Method of forming photographic images



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METHOD OF FORMING PHOTOGRAPHIC IMAG Jelis De Jonge, Hendrik Jonker, Klaas Jannes Kuening,

and Cornelis Johannes Dippel, Eindhoven, Netherlands, assignors, by mesne assignments, to North American Philips Company, Inc., New York, N. Y., a corporation of Delaware No Drawing. Application Septemher 18, 1956 Serial No. 610,676

Claims. (Cl. 96-48) Our invention relates to methods of forming photographic contrasts with the aid of light.

This application is a continuation-in-part of application Serial No. 248,102, filed September 24, 1951, now U. S. Patent No. 2,764,484. In that application we have disclosed that certain compositions, namely, metal complexes, upon exposure to light are capable of increasing the concentration of metallic mercury in the equilibrium Hgz++afls+++Hg by reacting with the mercuric ions and thus withdrawing them from the equilibrium.

In that application we have also disclosed, but not claimed, other compounds which serve the same purpose. One class of such compounds are aromatic bisulphite addition products and cyanohydrine derivatives of orthoor para-nitro substituted aromatic aldehydes corresponding to the formula:

wherein R is a phenyl group, and M is a radical selected from the group consisting of CN and SO H, and salts thereof. Examples of suitable compounds of this class are ortho-nitro mandelonitrile, para-nitro mandelonitrile,

bisulphite addition product of ortho-nitro-benzaldehyde v following examples.

Example I Superficially saponified acetyl-cellulose is soaked for 2 minutes in a 0.1 molar solution of orthoor para-nitrobenzaldehyde cyanohydrine in 40% ethanol, then wiped and dried. Subsequent to exposure under a negative with the u seof a mercury-vapor lamp this material is bathed for a short time in a 0.01 to 0.1 11 solution of mercurous nitrate in water; it is then physically developed in 0.5%

metol(p-methylamino phenol-sulfate)-2% c tric acid- 0.4% silver nitrate in water for 5 minutes. Very smart diapositive pictures of neutral grey to deep black in color, having an excellent half-tone reproduction and a great contrast effect are obtained.

Example ll superficially saponified acetylcellulose is soaked in a 0.1 molar solution of the potassium bisulphite addition product of ortho-nitro.benzaldehydein diluted ethanol, then'wiped and dried. Subsequent to exposure under a 1 negative with the use of a water-cooled mercury-vapor lamp this material is bathed for a short time in a 0.01 11 solution of mercurous nitrate in water; it is then physically developed for 5 minutes in a solution containing 0.5% metol, 2% citric acid and 0.4% silver nitrate in water. A neutral grey copy of the negative is obtained.

By using color-forming physical developers, such as described, for example, in U. S. application Serial No. 227,564, filed May 22, 1951, now U. S. Patent No. 2,750,292, a dye image may be produced in the area of and instead of the precious metal image. Then the precious metal image may, if necessary, be eliminated by means of one of the known attenuators, so that only a pigment image is left.

While we have described our invention in connection with specific embodiments and applications, other modifications thereof will be readily apparent to those skilled in this art without departing from the spirit and scope of the invention as defined in the appended claims.

What we claim is:

1. A method of producing photographic contrasts comprising the steps, selectively exposing a light-sensitive layer containing at least one aromatic compound corresponding to the general formula (NomGEf-H wherein n and m each have values selected from 0 and 1 and the sum of n-l-m equals 1, and M is a radical selected from the groug consisting of CN and SO H and then applying to said exposed layer a solution consisting of water and a water-soluble mercurous salt to form a latent mercury contrast, and physically developing the mercury contrast by applying to the mercury contrast an aqueous solution of a salt of a noble metal reducible to metal and a reducing agent for said metal so as to deposit said noble metal on said mercury contrast.

2. A method of producing photographic contrasts comprising the steps, selectively exposing a light sensitive layer containing ortho-nitro mandelonitrile, and then applying to said exposed layer an aqueous solution of a watersoluble mercurous salt to form a latent mercury contrast, and physically developing the mercury contrast by applying to the mercury contrast a solution consisting of water and a salt of a noble metal reducible to metal and a reducing agent for said metal so as to deposit said noble metal on said mercury contrast.

3. A method of producing photographic contrasts comprising the steps, selectively exposing a light sensitive layer containing para-nitro mandelonitrile, and then applying to saidexposed layer a solution consisting of water and a water-soluble mercurous salt to form a latent mercury contrast, and physically developing the mercury contrast by applying to the mercury contrast an aqueous solution consisting of water and a water-soluble mercurous salt to form a latent mercury contrast, and physically developing the mercury contrast by applying to the mercury contrast an aqueous solution of a salt of a noble metal Patented Jan. 13,- 1959 redhihle t'o metl and 3'- feducing agent for said" metl prddiict' of whfeh yild ah insoluble orgaui dye e'oiitfalst so= as to depositsaid noble metal on saidmercury consimultaneously in place with a metal contrast.

trast R r Ct d m fil f m t t 5. The method of dam 1 1n whlch a colo r photo- 6 erences l e m e 0 18 pa en rapfiiie on'trsf is use formed a'nd the reducing agent 5 UNITED STATES PATENTS 

1. A METHOD OF PRODUCING PHOTOGRAPHIC CONTRASTS COMPRISING THE STEPS, SELECTIVELY EXPOSING A LIGHT-SENSITIVE LAYER CONTAINING AT LEAST ONE AROMATIC COMPOUND CORRESPONDING TO THE GENERAL FORMULA 